Early heart and skeletal muscle mitochondrial response to a moderate hypobaric hypoxia environment

In eukaryotic cells, aerobic energy is produced by mitochondria through oxygen uptake. However, little is known about the early mitochondrial responses to moderate hypobaric hypoxia (MHH) in highly metabolic active tissues. Here, we describe the mitochondrial responses to acute MHH in the heart and skeletal muscle. Rats were randomly allocated into a normoxia control group (n = 10) and a hypoxia group (n = 30), divided into three groups (0, 6, and 24 h post-MHH). The normoxia situation was recapitulated at the University of Granada, at 662 m above sea level. The MHH situation was performed at the High-Performance Altitude Training Centre of Sierra Nevada located in Granada at 2320 m above sea level. We found a significant increase in mitochondrial supercomplex assembly in the heart as soon as the animals reached 2320 m above sea level and their levels are maintained 24 h post-exposure, but not in skeletal muscle. Furthermore, in skeletal muscle, at 0 and 6 h, there was increased dynamin-related protein 1 (Drp1) expression and a significant reduction in Mitofusin 2. In conclusion, mitochondria from the muscle and heart respond differently to MHH: mitochondrial supercomplexes increase in the heart, whereas, in skeletal muscle, the mitochondrial pro-fission response is trigged. Considering that skeletal muscle was not actively involved in the ascent when the heart was beating faster to compensate for the hypobaric, hypoxic conditions, we speculate that the different responses to MHH are a result of the different energetic requirements of the tissues upon MHH. KEY POINTS: The heart and the skeletal muscle showed different mitochondrial responses to moderate hypobaric hypoxia. Moderate hypobaric hypoxia increases the assembly of the electron transport chain complexes into supercomplexes in the heart. Skeletal muscle shows an early mitochondrial pro-fission response following exposure to moderate hypobaric hypoxia.

The Effects of Acute Deep Seawater Supplementation on Muscle Function after Triathlon

(1) Background: Trainers and athletes have always sought to reduce the failure of muscle function during long endurance events. However, nowadays, it is a topic that is generating much debate in the scientific field. Currently, deep-sea water (DSW) intake seems to be a suitable hydration alternative for this type of endurance event. Therefore, the aim of this study was to determine whether DSW consumption during a triathlon event could preserve muscle function after exercise. (2) Methods: Nineteen trained male triathletes (age = 39.0 ± 4.25 years; BMI = 23.67 ± 1.81 kg/m2) randomly performed three triathlons, one of them consuming DSW (Totum SPORT 30 AB, Laboratories Quinton International, S.L., Spain), the other consuming isotonic placebo and the last with tap water-hydration. A vertical jump test with countermovement and an isometric muscle strength test were conducted before and after the triathlon test. (3) Results: There was a significant difference between treatment × time during the isometric muscle strength test. Based on the Tukey post hoc analysis, the peak net force decreased statistically in the placebo (p = 0.045) and control conditions (p = 0.026), but not in the experimental condition (p = 0.121). In addition, all of the conditions studied obtained similar results in the countermovement vertical jump after exercise. (4) Conclusions: As a result, consumption of DSW seems to delay the failure of muscle function specifically in isometric exercises but does not improve performance in sports. Thus, DSW does not alter muscle capacity in a negative way; therefore, its consumption may be recommended.

Metabolic Adaptations to Morning Versus Afternoon Training: A Systematic Review and Meta-analysis

BACKGROUND

Some physiological responses such as circulating glucose as well as muscle performance show a circadian rhythmicity. In the present study we aimed to quantitatively synthesize the data comparing the metabolic adaptations induced by morning and afternoon training.

METHODS

PubMed, SCOPUS, and Web of Science databases were systematically searched for studies comparing the metabolic adaptations (> 2 weeks) between morning and afternoon training. A meta-analysis was performed using random-effects models with DerSimonian-Laird methods for fasting blood glucose, hemoglobin A1c (HbAc1), homeostatic model assessment (HOMA), insulin, triglycerides, total cholesterol, low-density lipoprotein (LDL), and high-density lipoprotein (HDL).

RESULTS

We identified 9 studies with 11 different populations (n = 450 participants). We found that afternoon exercise was more effective at reducing circulating triglycerides [standardized mean difference (SMD) - 0.32; 95% confidence interval (CI) - 0.616 to - 0.025] than morning training. Moreover, afternoon tended to decrease fasting blood glucose (SMD - 0.24; 95% CI - 0.478 to 0.004) to a greater extent than morning training.

CONCLUSION

Metabolic adaptations to exercise may be dependent on the time of day. Morning training does not show superior effects to afternoon exercise in any of the analyzed outcomes. However, afternoon training is more effective at reducing circulating triglyceride levels and perhaps at reducing fasting blood glucose than morning training. The study was preregistered at PROSPERO (CRD42021287860).

Mitochondrial Function and Signaling to Regulate Cellular Life

Mitochondria are essential organelles found in nearly all eukaryotic cells, responsible for producing the energy that drives cellular processes [...].

Mitochondrial adaptations to calorie restriction and bariatric surgery in human skeletal muscle: a systematic review with meta-analysis

OBJECTIVE

We performed a meta-analysis to determine the changes induced by calorie restriction (CR) and bariatric surgery on human skeletal muscle mitochondria.

METHODS

A systematic search of Medline and Web of Science was conducted. Controlled trials exploring CR (≥14 days) and mitochondrial function and/or content assessment were included. Moreover, studies analyzing weight loss following gastric surgery were included for comparison purposes. Human muscle data from 28 studies assessing CR (520 muscle samples) and from 10 studies assessing bariatric surgery (155 muscle samples) were analyzed in a random effect meta-analysis with three a priori chosen covariates.

MAIN RESULTS

We report a decrease (p < 0.05) (mean (95 % CI)) in maximal mitochondrial state 3 respiration in response to CR (-0.44 (-0.85, -0.03)) but not in response to surgery (-0.33 (-1.18, 0.52)). No changes in mitochondrial content were reported after CR (-0.05 (-0.12, 0.13)) or in response to surgery (0.23 (-0.05, 0.52)). Moreover, data from CR subjects showed a reduction in complex IV (CIV) activity (-0.29 (-0.56, -0.03)) but not in CIV content (-0.21 (-0.63, 0.22)). Similar results were obtained when the length of the protocol, the initial body mass index, and the estimated energy deficit were included in the model as covariates.

CONCLUSION

The observation of reduced maximal mitochondrial state 3, uncoupled respiration, and CIV activity without altering mitochondrial content suggests that, in human skeletal muscle, CR mainly modulates intrinsic mitochondrial function.

Does Hypoxia and Stress Erythropoiesis Compromise Cardiac Function in Healthy Adults? A Randomized Trial

OBJECTIVES

To investigate whether recombinant human erythropoietin (rHuEPO) injections during an altitude training camp impact heart function.

METHODS

Thirty (12 women) moderately trained subjects stayed at 2320 m altitude for 4 weeks while training. Subjects were randomized to placebo (isotonic saline) or rHuEPO (20 IU/kg body weight) i.v. injections. Transthoracic echocardiography imaging was acquired 3 days after arrival to altitude and prior to the first placebo or rHuEPO injection as well as one day after the last rHuEPO injection three weeks later.

RESULTS

rHuEPO did not alter cardiovascular morphology parameters, systolic or diastolic function. In the placebo group, altitude exposure improved left ventricle (LV) systolic function due to an increased twist angle but rHuEPO had no additional effects. Pulmonary arterial systolic pressure was unaffected in either group. Notably, rHuEPO hampered LV untwist rate without affecting LV early filling.

CONCLUSION

rHuEPO provided during mild altitude exposure does not cause any major effects on heart function. The observed alteration in LV untwist induced by rHuEPO is unlikely to have a meaningful clinical effect. Trial Registration Registered on www.

CLINICALTRIALS

gov (NCT04227665).

Physiological Benefits and Performance of Sea Water Ingestion for Athletes in Endurance Events: A Systematic Review

In different endurance events, athletes have limited access to fluid intake, such as ultra-endurance running. For this reason, it is necessary to establish an adequate hydration strategy for this type of long-duration sporting event. Indeed, it seems that the intake of seawater is a suitable hydration alternative to improve post-exercise recovery in this type of endurance event. This seawater is characterized by being a deep natural mineral water of moderate mineralization, which is usually extracted from a depth of about 700 m. Therefore, the aim of this systematic review is to evaluate the efficacy of seawater consumption in both performance and post-exercise recovery in long-duration sport events. A systematic and comprehensive literature search was performed in PubMed, Scopus, and Web of Science in September 2022. Initially, 8 out of 558 articles met the inclusion criteria. Among these eight studies, six were randomized clinical trials, and two were observational studies (one cross-sectional and one prospective study in well-conditioned student athletes). The results showed that deep sea water consumption accelerated the recovery of aerobic capacity and leg muscle capacity on running performance. In addition, the lactate production after the running exercise in seawater was significantly lower than in pure water. In conclusion, the present review demonstrates that seawater consumption could significantly improve the capacity of recovery after exercise.

Seawater Hydration Modulates IL-6 and Apelin Production during Triathlon Events: A Crossover Randomized Study

A triathlon is an endurance event in which athletes need an efficient hydration strategy since hydration is restricted at different stages. However, it seems that seawater intake can be a suitable hydration alternative for this type of endurance event. Therefore, the aim of this study was to evaluate the efficacy of seawater hydration during a triathlon on cytokine production. Fifteen trained male triathletes (age = 38.8 ± 5.62 years old; BMI = 22.58 ± 2.51 kg/m²) randomly performed three triathlons, one of them consuming seawater (Totum SPORT, Laboratories Quinton International, S.L., Valencia, Spain), the other one consuming tap water ad libitum, and the last a physiologic saline solution as placebo. The triathlon consisted of an 800 m swim, a 90 km bike ride, and a 10 km run. Blood samples were taken at rest and after training, where markers of inflammation, hemoglobin, and hematocrit concentration were assessed. While the seawater was not ergogenic, it significantly increased the release of IL-6 and apelin post-exercise. However, no differences were found between the fractalkine, IL-15, EPO, osteonectin, myostatin, oncostatin, irisin, FSTL1, osteocrin, BDNF, and FGF-21 values over those of the placebo group. The present study demonstrates that hydration with seawater stimulates myokine production, which could lead to improved performance recovery after exercise.

Physiological Doses of Hydroxytyrosol Modulate Gene Expression in Skeletal Muscle of Exercised Rats

We tested whether physiological doses of hydroxytyrosol (HT) may alter the mRNA transcription of key metabolic genes in exercised skeletal muscle. Two groups of exercise-trained Wistar rats, HTlow and HTmid, were supplemented with 0.31 and 4.61 mg/kg/d of HT, respectively, for 10 weeks. Another two groups of rats were not supplemented with HT; one remained sedentary and the other one was exercised. After the experimental period, the soleus muscle was removed for qRT-PCR and western blot analysis. The consumption of 4.61 mg/kg/d of HT during exercise increased the mRNA expression of important metabolic proteins. Specifically, 4.61 mg/kg/d of HT may upregulate long-chain fatty acid oxidation, lactate, and glucose oxidation as well as mitochondrial Krebs cycle in trained skeletal muscle. However, a 4.61 mg/kg/d of HT may alter protein translation, as in spite of the increment showed by CD36 and GLUT4 at the mRNA level this was not translated to higher protein content.

Assessment of the Phytochemical and Nutrimental Composition of Dark Chia Seed (Salvia hispánica L.)

Chia seeds are rich sources of different macro and micronutrients associated with health benefits; thus, they may be considered as a functional food. However, the composition depends on the variety, origin, climate and soil. Here, we show a comprehensive characterization of extractable and non-extractable phenolic compounds of dark chia seed Salvia hispanica L. using high-performance liquid chromatography-electrospray ionization-quadrupole time-of-flight (HPLC-ESI-QTOF) and discuss potential health benefits associated with the presence of a number of nutritional and bioactive compounds. We report that dark chia from Jalisco is a high-fiber food, containing omega-3 polyunsaturated fatty acids, essential amino acids (phenylalanine and tryptophan), and nucleosides (adenosine, guanidine and uridine), and rich in antioxidant phenolic compounds, mainly caffeic acid metabolites. Our data suggest that chia seeds may be used as ingredients for the development of functional foods and dietary supplements.

Hydroxytyrosol modifies skeletal muscle GLUT4/AKT/Rac1 axis in trained rats

Training induces a number of healthy effects including a rise in skeletal muscle (SKM) glucose uptake. These adaptations are at least in part due to the reactive oxygen species produced within SKM, which is in agreement with the notion that antioxidant supplementation blunts some training-induced adaptations. Here, we tested whether hydroxytyrosol (HT), the main polyphenol of olive oil, would modify the molecular regulators of glucose uptake when HT is supplemented during exercise. Rats were included into sedentary and exercised (EXE) groups. EXE group was further divided into a group consuming a low HT dose (0.31 mg·kg·d; EXElow), a moderate HT dose (4.61 mg·kg·d; EXEmid), and a control group (EXE). EXE raised glucose transporter type 4 (GLUT4) protein content, Ras-related C3 botulinum toxin substrate 1 (Rac1) activity, and protein kinase b (AKT) phosphorylation in SKM. Furthermore, EXElow blunted GLUT4 protein content and AKT phosphorylation while EXEmid showed a downregulation of the GLUT4/AKT/Rac1 axis. Hence, a low-to-moderate dose of HT, when it is supplemented as an isolated compound, might alter the beneficial effect of training on basal AKT phosphorylation and Rac1 activity in rats.

Functional role of respiratory supercomplexes in mice: SCAF1 relevance and segmentation of the Qpool

Mitochondrial respiratory complexes assemble into supercomplexes (SC). Q-respirasome (III2 + IV) requires the supercomplex assembly factor (SCAF1) protein. The role of this factor in the N-respirasome (I + III2 + IV) and the physiological role of SCs are controversial. Here, we study C57BL/6J mice harboring nonfunctional SCAF1, the full knockout for SCAF1, or the wild-type version of the protein and found that exercise performance is SCAF1 dependent. By combining quantitative data-independent proteomics, 2D Blue native gel electrophoresis, and functional analysis of enriched respirasome fractions, we show that SCAF1 confers structural attachment between III2 and IV within the N-respirasome, increases NADH-dependent respiration, and reduces reactive oxygen species (ROS). Furthermore, the expression of AOX in cells and mice confirms that CI-CIII superassembly segments the CoQ in two pools and modulates CI-NADH oxidative capacity.

The emerging role of skeletal muscle mitochondrial dynamics in exercise and ageing

Mitochondria are the hub for energy production within living cells. They can undergo morphological changes in response to nutrient availability and cellular stress. Here, we review how exercise chronically and acutely affects mitochondrial dynamics. Moreover, we discuss whether mitochondrial dysfunction observed in elderly subjects is due to the ageing process per se or due to the associated sedentary state. Finally, we study how endurance exercise can improve mitochondrial dynamics in older subjects, thereby improving their overall health and likely limiting muscle waste.

Differential IL 10 serum production between an arm-based and a leg-based maximal resistance test

Bench press (i.e. arm-based) and half-squat (i.e. leg-based) are exercises commonly used to increase and evaluate muscular strength. In addition to differences in the location of the muscles that participate in each exercise, the total muscle mass required for the latter is larger than that involved in the former. The aim of this study is to analyze the effects of a maximal incremental strength test when performed by bench press and by half-squat on myocellular damage, oxidative damage and the inflammatory cytokine response. Ten male athletes were subjected to half-squat and bench press incremental strength tests. Blood samples were collected at rest, 15-minutes and 24 h post-test. Hydroperoxide and malondialdehyde concentrations were determined as lipid peroxidation markers. Lactate dehydrogenase (LDH) and creatine kinase isoenzyme MB (CK-MB) activities were determined as markers of muscle damage. α-Actin concentration was determined as a marker of sarcomeric damage. Serum interleukin (IL) 6, IL10, and tumor necrosis factor alpha (TNFα) were determined to assess the inflammatory response. LDH and CK-MB values were greater at 15 min and 24 h post bench press exercise (p < 0.05). No differences were found in lipid peroxidation or α-actin. Interestingly, IL10 values were greater in response to the press bench at 24 h post-test (p < 0.05). Our results suggest that, at equivalent workloads, an arm-based exercise induced higher anti-inflammatory effects and more severe muscle damage compared with a leg-based exercise.

Acute/Subacute and Sub-Chronic Oral Toxicity of a Hidroxytyrosol-Rich Virgin Olive Oil Extract

The objective of this study was to determine the acute (one single dose), subacute (14 days), and sub-chronic (90 days) toxicity of an aqueous virgin olive oil (VOO) extract rich in hydroxytyrosol in rats. For acute/subacute toxicity, rats were divided into three groups. The control group received distilled water (n = 9), another experimental group received a single dose of 300 mg/kg (n = 3), and a third group received one dose of 2000 mg/kg (n = 4) during 14 days. The sub-chronic study included 60rats distributed in three groups (n = 20: 10 males and 10 females) receiving daily different three doses of the VOO extract in the drinking water during 90 days: (1) 100 mg/kg, (2) 300 mg/kg, and (3) 1000 mg/kg. In parallel, a fourth additional group (n = 20: 10 males and 10 females) did not receive any extract (control group). Clinical signs, body weight, functional observations of sensory and motor reactivity, hematological and biochemical analyses, and macroscopic and microscopic histopathology were evaluated. No adverse effects were observed after the administration of the different doses of the hydroxytyrosol-rich VOO extract, which suggests that the enrichment of VOO in its phenolic compound is safe, and can be used as functional foods for the treatment of chronic degenerative diseases.

Human muscular mitochondrial fusion in athletes during exercise

The main objective of this work was to investigate whether mitochondrial fusion occurs in the skeletal muscle of well-trained athletes in response to high-intensity exercise. Well-trained swimmers (n = 9) performed a duration-matched sprint interval training (SIT) and high-intensity high-volume training (HIHVT) session on separate days. Muscle samples from triceps brachii were taken before, immediately after, and 3 h after the training sessions. Transmission electron microscopy (TEM) was applied to assess mitochondrial morphology. Moreover, expression of genes coding for regulators of mitochondrial fusion and fission were assessed by real-time quantitative PCR. In addition, mitofusin (MFN)2 and optic atrophy 1 (OPA1) were quantified by Western blot analysis. TEM analyses showed that mitochondrial morphology remained altered for 3 h after HIHVT, whereas SIT-induced changes were only evident immediately after exercise. Only SIT increased MFN1 and MFN2 mRNA expression, whereas SIT and HIHVT both increased MFN2 protein content 3 h after exercise. Notably, only HIHVT increased OPA1 protein content. Mitochondrial morphologic changes that suggest fusion occurs in well-adapted athletes during exercise. However, HIHVT appears as a more robust inducer of mitochondrial fusion events than SIT. Indeed, SIT induces a rapid and transient change in mitochondrial morphology.-Huertas, J. R., Ruiz-Ojeda, F. J., Plaza-Díaz, J., Nordsborg, N. B., Martín-Albo, J., Rueda-Robles, A., Casuso, R. A. Human muscular mitochondrial fusion in athletes during exercise.

Hydroxytyrosol influences exercise-induced mitochondrial respiratory complex assembly into supercomplexes in rats

Hydroxytyrosol (HT) has been demonstrated to improve mitochondrial function, both in sedentary and in exercised animals. Herein, we assessed the effects of two different doses of HT on exercise-induced mitochondrial respiratory complex (C) assembly into supercomplexes (SCs) and the relation of the potential results to OPA1 levels and oxidative stress. Wistar rats were allocated into six groups: sedentary (SED), sedentary consuming 20 mg/kg/d of HT (SED-20), sedentary consuming 300 mg/kg/d of HT (SED-300); exercised (EXE), exercised consuming 20 mg/kg/d of HT (EXE-20) and exercised consuming 300 mg/kg/d of HT (EXE-300). Animals were exercised and/or supplemented for 10 weeks, and assembly of SCs, mitochondrial oxidative status and expression of OPA1 were quantified in the gastrocnemius muscle. Both EXE and EXE-20 animals exhibited increased assembly of CI into SCs, but this effect was absent in EXE-300 animals. Levels of CIII₂ assembled into SCs were only increased in EXE-20 animals. Notably EXE-300 animals showed a decreased relative expression of s-OPA1 isoforms. Therefore, HT exerted dose-dependent effects on SC assembly in exercised animals. Although the mechanisms leading to SCs assembly in response to exercise and HT are unclear, it seems that a high HT dose can prevent SCs assembly during exercise by decreasing the expression of the s-OPA1 isoforms.

Effects of hydroxytyrosol dose on the redox status of exercised rats: the role of hydroxytyrosol in exercise performance

Background

Hydroxytyrosol (HT) is a polyphenol found in olive oil that is known for its antioxidant effects. Here, we aimed to describe the effects of a low and high HT dose on the physical running capacity and redox state in both sedentary and exercised rats.

Methods

Male Wistar rats were allocated into 6 groups: sedentary (SED; n = 10); SED consuming 20 mg/kg/d HT (SED20; n = 7); SED consuming 300 mg/kg/d HT (SED300; n = 7); exercised (EXE; n = 10); EXE consuming 20 mg/kg/d HT (EXE20; n = 10) and EXE consuming 300 mg/kg/d HT (EXE300; n = 10). All the interventions lasted 10 weeks; the maximal running velocity was assessed throughout the study, whereas daily physical work was monitored during each training session. At the end of the study, the rats were sacrificed by bleeding. Hemoglobin (HGB) and hematocrit (HCT) were measured in the terminal blood sample. Moreover, plasma hydroperoxide (HPx) concentrations were quantified as markers of lipid peroxidation.

Results

In sedentary rats, HT induced an antioxidant effect in a dose-dependent manner without implications on running performance. However, if combined with exercise, the 300 mg/kg/d HT dosage exhibited a pro-oxidant effect in the EXE300 group compared with the EXE and EXE20 groups. The EXE20 rats showed a reduction in daily physical work and a lower maximal velocity than the EXE and EXE300 rats. The higher physical capacity exhibited by the EXE300 group was achieved despite the EXE300 rats expressing lower HGB levels and a lower HCT than the EXE20 rats.

Conclusions

Our results suggest that a high HT dose induces a systemic pro-oxidant effect and may prevent the loss of performance that was observed with the low HT dose.

Comparison of the inflammatory and stress response between sprint interval swimming and running

The aim of the study was to compare myocellular damage, metabolic stress, and inflammatory responses as well as circulating sodium (Na⁺ ) and potassium (K⁺ ) between a single sprint swimming and running training. Eighteen subjects regularly involved in swimming and running training for at least 2 years were recruited. The subjects performed 8 × 30 seconds "all out" exercise on different days either by running or by swimming in a random order. Blood was collected before each training session, after the cessation of exercise (post) and after 2 hours of rest (2 hours). We then analyzed tumor necrosis factor alpha (TNF-α), interleukin 10 (IL-10), interleukin 6 (IL-6), cortisol, creatine kinase MB isoform (CK-MB), lactate dehydrogenase (LDH), K⁺ , and Na⁺ . Neither TNF-α nor IL-10 differed between swimming and running. Most of the subjects showed a non-statistically significant increase of LDH and CK-MB after swimming. On the other hand, IL-6 (P < .05) and cortisol (P < .05) were significantly lower after 2 hours of swimming than after running. In addition, post-exercise K⁺ was significantly lower (P < .001) for swimming than for running. Our results provide evidence of similar inflammatory responses between exercise modes but lower metabolic stress in response to swimming than in response to running.

High-intensity high-volume swimming induces more robust signaling through PGC-1α and AMPK activation than sprint interval swimming in m. triceps brachii

We aimed to test whether high-intensity high-volume training (HIHVT) swimming would induce more robust signaling than sprint interval training (SIT) swimming within the m. triceps brachii due to lower metabolic and oxidation. Nine well-trained swimmers performed the two training procedures on separate randomized days. Muscle biopsies from m. triceps brachii and blood samples were collected at three different time points: a) before the intervention (pre), b) immediately after the swimming procedures (post) and c) after 3 h of rest (3 h). Hydroperoxides, creatine kinase (CK), and lactate dehydrogenase (LDH) were quantified from blood samples, and peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) and the AMPK^pTHR172/AMPK ratio were quantified by Western blot analysis. PGC-1α, sirtuin 3 (SIRT3), superoxide-dismutase 2 (SOD2), and vascular endothelial growth factor (VEGF) mRNA levels were also quantified. SIT induced a higher release of LDH (p < 0.01 at all time points) and CK (p < 0.01 at post) than HIHVT, but neither SIT nor HIHVT altered systemic hydroperoxides. Additionally, neither SIRT3 nor SOD2 mRNA levels increased, while PGC-1α transcription increased at 3 h after SIT (p < 0.01) and after HIHVT (p < 0.001). However, PGC-1α protein was higher after HIHVT than after SIT (p < 0.05). Moreover, the AMPK^pTHR172/AMPK ratio increased at post after SIT (p < 0.05), whereas this effect was delayed after HIHVT as it increased after 3 h (p < 0.05). In addition, VEGF transcription was higher in response to HIHVT (p < 0.05). In conclusion, SIT induces higher muscular stress than HIHVT without increasing systemic oxidation. In addition, HIHVT may induce more robust oxidative adaptations through PGC-1α and AMPK.

Antioxidant effect of exercise: Exploring the role of the mitochondrial complex I superassembly

Mitochondrial respiratory complexes become assembled into supercomplexes (SC) under physiological conditions. One of the functional roles of these entities is the limitation of reactive oxygen species (ROS) produced by complex I (CI) of the respiratory chain. We sought to determine whether the systemic antioxidant effect of exercise is mediated by the assembly of mitochondrial CIs into SCs in rats. Male Wistar rats were exercise trained or remained sedentary for ten weeks; then, blood samples were collected, and the gastrocnemius muscle was isolated. The assembly of mitochondrial SCs and the lipid peroxidation of the mitochondrial and plasmatic fractions were assessed. Our results demonstrate that exercise induced the assembly of CI into SCs in the gastrocnemius and induced a systemic decrease in lipid peroxidation. We also found an inverse association between the superassembly of CIs and mitochondrial lipid peroxidation (p < 0.01) and protein carbonyls (p < 0.05). We conclude that exercise induces the chronic assembly of CIs into SCs, which provide mitochondrial protection against oxidative damage, at least in the studied muscle. Given the relevant role that mitochondria play in health and disease, these findings should help to elucidate the role of exercise as a therapeutic approach for metabolic diseases.

Does Swimming at a Moderate Altitude Favor a Lower Oxidative Stress in an Intensity-Dependent Manner? Role of Nonenzymatic Antioxidants

Casuso, Rafael A., Jerónimo Aragón-Vela, Gracia López-Contreras, Silvana N. Gomes, Cristina Casals, Yaira Barranco-Ruiz, Jordi J. Mercadé, and Jesus R. Huertas. Does swimming at a moderate altitude favor a lower oxidative stress in an intensity-dependent manner? Role of nonenzymatic antioxidants. High-Alt Med Biol. 18:46-55, 2017.-we aimed to describe oxidative damage and enzymatic and nonenzymatic antioxidant responses to swimming at different intensities in hypoxia. We recruited 12 highly experienced swimmers who have been involved in competitive swimming for at least 9 years. They performed a total of six swimming sessions carried out at low (LOW), moderate (MOD), or high (HIGH) intensity at low altitude (630 m) and at 2320 m above sea level. Blood samples were collected before the session (Pre), after the cool down (Post), and after 15 minutes of recovery (Rec). Blood lactate (BL) and heart rate were recorded throughout the main part of the session. Average velocities did not change between hypoxia and normoxia. We found a higher BL in response to MOD intensity in hypoxia. Plasmatic hydroperoxide level decreased at all intensities when swimming in hypoxia. This effect coincided with a lower glutation peroxidase activity and a marked mobilization of the circulating levels of α-tocopherol and coenzyme Q10 in an intensity-dependent manner. Our results suggest that, regardless of the intensity, no oxidative damage is found in response to hypoxic swimming in well-trained swimmers. Indeed, swimmers show a highly efficient antioxidant system by stimulating the mobilization of nonenzymatic antioxidants.

Control of antioxidant supplementation through interview is not appropriate in oxidative-stress sport studies: Analytical confirmation should be required

OBJECTIVE

Controlling antioxidant supplementation in athletes involved in studies related to oxidative stress and muscle damage is the key to ensure results. The aim of this study was to confirm through high-performance liquid chromatography (HPLC) analysis whether well-trained individuals lied during a personal interview when asked if they were taking supplements with antioxidants, and how this could affect oxidative stress, muscle damage, and antioxidant response.

METHODS

A total of 94 men, well trained in endurance sports, volunteered in this study. They denied taking any antioxidant supplementation at initial interview. After a HPLC analysis, abnormal α-tocopherol concentrations were detected, probably due to a hidden antioxidant supplementation. Participants were classified into two groups: no evidence of antioxidant supplementation (NS group = α-tocopherol values <80 nmol/mL; n = 75) and evidence of antioxidant supplementation (S group = α-tocopherol values >80 nmol/mL; n = 19). Lipid peroxidation, muscle damage, antioxidant enzyme activity, and nonenzymatic antioxidant content were analyzed according to this classification. Statistical comparisons were performed using Student's t test.

RESULTS

The α-tocopherol concentrations were significantly higher in the S group than in the NS group (MD = 725.01 ± 39.01 nmol/mL; P = 0.001). The S group showed a trend toward lower hydroperoxides than the NS group (MD = 1.19 ± 0.72 nmol/mL; P = 0.071). The S group showed significantly lower catalase activity than the NS group (MD = 0.10 ± 0.02-seg-1 mg-1; P < 0.01). Skeletal muscle damage markers did not differ between experimental groups.

CONCLUSIONS

Data from the present study reveal that 20% of participants lied in the exclusion criteria of antioxidant supplementation in a personal interview, as they showed high plasmatic α-tocopherol concentrations after HPLC verification. Catalase activity seems to be affected by high α-tocopherol plasma levels. Therefore, we strongly recommend the HPLC analysis as a necessary tool to verify the antioxidant intake and preserve results in studies linking oxidative stress and sport.

Effects of a six-week Pilates intervention on balance and fear of falling in women aged over 65 with chronic low-back pain: A randomized controlled trial

OBJECTIVE

The purpose of our study was to evaluate the effects of six weeks of Pilates regarding functional balance, fear of falling and pain in community living women older than 65 years old with chronic low-back pain.

STUDY DESIGN

A single blind controlled randomized trial of six weeks of Pilates in addition to physiotherapy treatment (n=50) vs. physiotherapy treatment alone (n=47) was conducted on 97 community living women (71.14 ± 3.30 years) with chronic low-back pain (CLBP).

MAIN OUTCOME MEASURES

Main outcome measures were fear of falling (FoF), assessed by the Falls Efficacy Scale-international; functional mobility and balance, measured with the Timed up and Go Test; and pain, evaluated using the numeric rating scale.

RESULTS

Only the Pilates group showed improvement in FoF (ES; d=.68) and functional mobility and balance (ES; d=1.12) after treatment, and also had better results in pain (ES; d=1.46) than the physiotherapy-only group.

CONCLUSIONS

Six weeks of Pilates exercises may be effective in fall prevention through the improvement of FoF, functional balance, and pain in Spanish women over 65 years old with CLBP.

Effects of in-water passive recovery on sprint swimming performance and heart rate in adolescent swimmers

The aim of the present study is to test the hypothesis that sprint swimming performance is enhanced by in-water passive recovery (IN) after sprint swimming bouts in well-trained adolescent swimmers. Using a randomized crossover study design, twelve well-trained adolescent swimmers performed two tests at the swimming pool after preliminary testing. They performed 5 bouts of 100m all-out swimming separated by 5 minutes of passive rest. Their individual in- or out-of-water passive recovery condition was randomized on the first day. In their second visit to the swimming pool the opposite recovery condition was indicated. More than 60% of the subjects which rested in-water were faster in the 5th bout when compared to the OUT group. However, no significant differences were found in blood lactate when IN and OUT were compared. After the first bout peak heart rate (HR peak) was lower in subsequent bouts for IN recovery when compared with OUT (p < 0.001). Thus, coaches and researchers should take into account that IN passive recovery may decrease loss of performance and diminish HR peak during sprint swimming bouts. This is particularly important given the use that many coaches give to HR as a tool in daily training. Key pointsIn-water passive recovery minimizes the loss of performance during high intensity swimmingMaximal HR is significantly reduced by in-water recoveryCoaches should take this information into account when using HR to control swimming intensityFuture research should study long-term effects induced by in-water passive recovery.

Quercetin effects on weight gain and caloric intake in exercised rats

Quercetin is a flavonoid which activates oxidative metabolism. Quercetin may reduce weight gain by decreasing feed efficiency. The present study aims to evaluate weight gain, caloric intake and feed efficiency in exercised and sedentary rats supplemented with quercetin. Wistar rats were divided into four groups: quercetin-exercise training (QT), quercetin-sedentary (QS), placebo-exercise training (PT) and placebo-sedentary (PS). Rats were exercised and/or orally supplemented with quercetin (25 mg · kg⁻¹ on alternate days) during six weeks. Weight gain of the QT group decreased when compared with the PT and PS groups. Exercised groups increased cumulative caloric intake during the experimental period. The QT group rats also reduced their feed efficiency when compared with the QS and PS groups. These results suggest that quercetin is not able to decrease weight gain because no differences were found between placebo and quercetin condition either in the sedentary or in the training condition.

Oral quercetin supplementation hampers skeletal muscle adaptations in response to exercise training

We aimed to test exercise-induced adaptations on skeletal muscle when quercetin is supplemented. Four groups of rats were tested: quercetin sedentary, quercetin exercised, placebo sedentary, and placebo exercised. Treadmill exercise training took place 5 days a week for 6 weeks. Quercetin groups were supplemented with quercetin, via gavage, on alternate days throughout the experimental period. Sirtuin 1 (SIRT1), peroxisome proliferator-activated receptor γ coactivator-1α mRNA levels, mitochondrial DNA (mtDNA) content, and citrate synthase (CS) activity were measured on quadriceps muscle. Redox status was also quantified by measuring muscle antioxidant enzymatic activity and oxidative damage product, such as protein carbonyl content (PCC). Quercetin supplementation increased oxidative damage in both exercised and sedentary rats by inducing higher amounts of PCC (P < 0.001). Quercetin supplementation caused higher catalase (P < 0.001) and superoxide dismutase (P < 0.05) activity in the non-exercised animals, but not when quercetin is supplemented during exercise. Quercetin supplementation increased SIRT1 expression, but when quercetin is supplemented during exercise, this effect is abolished (P < 0.001). The combination of exercise and quercetin supplementation caused lower (P < 0.05) mtDNA content and CS activity when compared with exercise alone. Quercetin supplementation during exercise provides a disadvantage to exercise-induced muscle adaptations.

Plasmatic nitric oxide correlates with weight and red cell distribution width in exercised rats supplemented with quercetin

Quercetin is suggested as a nitric oxide regulator which may in turn influence blood parameters and weight gain. Wistar rats were classified as: quercetin-exercise training, QT; placebo-exercise training, PT; quercetin-sedentary, QS; and placebo sedentary, PS. After 6 weeks of treatment with quercetin and/or exercise, an incremental test was run to measure oxygen consumption. QT had lower levels of NO compared with PS (p = 0.029) and QS (p = 0.002). Red cell distribution width increased in both exercised groups, especially in the QT group (p < 0.001). Pearson correlation analysis showed that nitric oxide levels were associated with weight (r = 0.675) and red distribution width (r = -0814) in the QT group. Quercetin effect on NO production seems to be more powerful when it is supplemented during exercise training. Moreover, RDW relationship with NO production need to be further investigated in regards to health.

Ergogenic effects of quercetin supplementation in trained rats

BACKGROUND

Quercetin is a natural polyphenolic compound currently under study for its ergogenic capacity to improve mitochondrial biogenesis. Sedentary mice have exhibited increased endurance performance, but results are contradictory in human models.

METHODS

We examined the effects of six weeks of endurance training and quercetin supplementation on markers of endurance performance and training in a rodent model. Rats were randomly assigned to one of the following groups: placebo+sedentary (PS), quercetin+sedentary (QS), placebo+endurance training (PT) and quercetin+endurance training (QT). Quercetin was administered at a dose of 25 mg/kg on alternate days. During six weeks of treatment volume parameters of training were recorded, and after six weeks all groups performed a maximal graded VO2 max test and a low-intensity endurance run-to-fatigue test.

RESULTS

No effects were found in VO2 peak (p>0.999), nor in distance run during low-intensity test, although it was 14% greater in QT when compared with PT (P = 0.097). Post-exercise blood lactate was increased in QT when compared with PT (p=0.023) and also in QS compared with PS (p=0.024).

CONCLUSIONS

This study showed no effects in VO2 peak, speed at VO2 peak or endurance time to exhaustion after six weeks of quercetin supplementation compared with placebo in trained rats. Quercetin was show to increase blood lactate production after high-intensity exercise.